While admitting "the idea of standing again has its romance", he argued the importance of "leading from the front" in May's local elections.

His decision is a blow to Ukip's chances of causing a shock result in Eastleigh. The party's campaign would have benefited from their leader's high profile and the fact he stood for election in the Hampshire town in 1994, beating Screaming Lord Sutch of the Monster Raving Loony Party by 169 votes.

"Whoever is chosen will have my full support, and the support of everyone in the party," he added.

"We will fight this by-election as hard as we can, and expect to turn what people predict to be a two-way fight into a serious political battle."

Without Farage's presence the Ukip candidate may yet benefit from coalition infighting, as Conservatives pour their frustrations with the Liberal Democrats into a campaign against Nick Clegg's party.

This is the first seat being defended by the Lib Dems since the formation of the coalition government in 2010 - and comes after former energy and climate change secretary Chris Huhne pleaded guilty to perverting the course of justice in court yesterday.